Re: [PATCH v2 2/9] mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range()

[Muchun Song]

On Fri, Jun 24, 2022 at 08:51:46AM +0900, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> 
> Originally copy_hugetlb_page_range() handles migration entries and hwpoisone
> entries in similar manner.  But recently the related code path has more code
> for migration entries, and when is_writable_migration_entry() was converted
> to !is_readable_migration_entry(), hwpoison entries on source processes got
> to be unexpectedly updated (which is legitimate for migration entries, but
> not for hwpoison entries).  This results in unexpected serious issues like
> kernel panic when foking processes with hwpoison entries in pmd.
> 
> Separate the if branch into one for hwpoison entries and one for migration
> entries.
> 
> Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>

Thanks for fixing it.

Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>